The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
50. (The passage enjoining bâlya means that the ascetic is to live) not manifesting himself; on account of the connexion (thus gained for the passage).
The passage, 'Therefore let a Brâhmana after he has done with learning wish to stand by a childlike state,' speaks of the childlike state as something to be undertaken. Now by the 'childlike state' we have to understand either the nature or the actions of a child. Childhood in so far as it means a period of life cannot be brought about at will, and we therefore must take the 'childlike state' to mean either the behaviour of a child--such as attending to the calls of nature without any respect of place, &c.--or inward purity, i.e. absence of cunning, arrogance, force of the sensual passions, and so on 1.--With regard to the
doubt thus arising the pûrvapakshin maintains that by 'childlike being' people more commonly understand behaving, talking, and eating according to one's liking, freely attending to the calls of nature and so on, and that therefore the word is to be understood here also in that sense.--But such free conduct is improper, because sinfulness and so on would follow from it!--Not so, the pûrvapakshin replies; for the Samnyâsin possessing knowledge is, through express scriptural statements, free from all sinfulness thus incurred; just as the sacrificer is declared to be free from the sin he might incur in slaying the sacrificial animal.
To this we reply that it is not so because the statement of the text may be understood in a different sense. For as long as another rational interpretation of the word 'bâlya' is possible we have no right to adopt an interpretation which involves the assumption of another injunction being rendered futile. Moreover subordinate matters are enjoined with a view to the furtherance of the principal matter, and what here is the principal matter is the endeavour after knowledge which ascetics have to take upon themselves. Now if we accepted the entire conduct of a child as what is enjoined here we could in no way show that the endeavour of knowledge is furthered thereby. We therefore understand by 'bâlya' the special inward state of a child, i.e. absence of strong sensual passions and the like. This the Sûtra expresses by saying 'Not manifesting.' The meaning of the clause under discussion thus is: Let him be free from guile, pride, and so on, not manifesting himself by a display of knowledge, learning, and virtuousness, just as a child whose sensual powers have not yet developed themselves does not strive to make a display of himself before others. For thus the passage gains a connexion with the entire chapter on the ground of co-operating towards the principal matter. In agreement herewith Smriti-writers have said, 'He whom nobody knows either
as noble or ignoble, as ignorant or learned, as well-conducted or ill-conducted, he is a Brâhmana. Quietly devoted to his duty, let the wise man pass through life unknown; let him step on this earth as if he were blind, unconscious, deaf.' Another similar passage is, 'With hidden nature, hidden conduct,' and so on.
325:1 I am doubtful as to the true reading in this place. The 'va' of the Calcutta edition (p. 1039, last line) has certainly to be struck p. 326 out. Some good MSS. read:--bâlakaritam antargatâ bhâvavisuddhir aprarûdhendriyatvam dambhâdirahitatvam vâ.--The 'antargatâ' seems to mean the same as the 'ântarah.' p.1041, II, 1-2.